Air conditioners and controls therefor



5 Sheets-Sheet 1 T. G. CRIDER AIR CONDITIONERS AND CONTROLS THEREFOR Jan. l5, 1963 Filed Jan. 21, 1959 @Ziff Z mm m wf ,mm NNW. fw .wx

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Jan. l5, 1963 T. G. cRxDER 3,073,132

' AIR CONDITIONERS AND CONTROLS THEREFOR Filed Jan. 2l, 1959 5 Sheets-Sheet 2 INVENTOR 750A/isf F/ae ATTORNEYS Jan. 15, 1963 T. G. cRlDER 3,073,132

AIR CONDITIONERS AND CONTROLS THEREFOR Filed Jan. 2l, 1959 5 Sheets-Sheet 5 ATTORNEYS Jan. 15, 1963 T. G. CRIDER 3,073,132

AIR CONDITIONERS AND CONTROLS THEREFOR Filed Jan. 21, 1959 5 Sheets-Sheet 4 .z 7 .ZU

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INVENTOR 7670/1445 5 (2D/a A? y@ VM ATTORNEYS Jan. 15, 1963 T. G. cRxDl-:R 3,073,132

AIR CONDITIONERS AND CONTROLS THEREFOR Filed Jan. 21, 1959 5 sheets-sheet s INVENTOR fms fe/af BY www ATTORNEYS l AIR coNDIrIoNERs. AND CONTROLS. Treinstation.

Thomas G1.H Crider, Lakewood, Ohio, assgnorto Hpp.:

Corporation, Cleveiand, Ohio, a corporation of Virginia Filed Jan. 21, 1959, Ser. No. 788,104

Claims. Cl. 62--183) This invention relates to air conditioning systems andmore particularly to methods and controls for modulating the capacity of air conditioning assemblies to provide novel humidity and ventilation regulation and to avoid operational diiculties resulting from variations in ambient temperature.

As used herein the term air conditioning systems and similar expressions are intended to embrace apparatus of the heat pump types as well as units which are effective only to cool the space to be served by the units.

In one of its aspects, the invention is concerned with central air-conditioning systems of the-type employing-al centrifugal blower to draw air over evaporatingcoils and impel it through distributingv ducts to a space to vbe cooled. In such systems the blower and refrigeration unit have operating `characteristics conforming toA 'standards which have been predetermined by the manufacturer -based upon' average'service conditions for similar units.- vIn-a given installation of such a system, however, variable is 'introduced which will appreciably affect the lsystems ability to operate satisfactorily and which is not factory-control# lable under practicable manufacturing conditions; More specically, the variants inv static pressure (depending upon the ducting lengths, ducting cross-sectional `area and particular configuration of the ducting system) will substantially alter the performance of a given system. Thus, with a tortuousducting conliguration, a different quantity of ail per unit of time will be provided than with ducting of linear construction.

In the past, adjustment for variationsin static pressure and other variablesina given air conditioningsystem at the site of the installation wasaccomplished by laborious adjustment of complex damper arrangements which were unsatisfactory in operation.

In addition to-the dii'liculty discussed above, additional problems are created due to humidity variations. Most air conditioning systems in current use `are equipped with thermostatic controls which are responsive solely to ilu`c" tuations'iin temperature. The conventional type of thermostate is an on-oft device which is adapted to either turn the blower on and ott' or, alternatively, to cycle the compressor-condenser-evaporator system. Conventional cooling systems are not equipped with a separate humidity control and, to applicants knowledge, no such control is available which is both reliable and inexpensive enough to be usable in such systems. j

Still another aspect of this invention relates to the prevention of icing on the surfaces of the evaporator coil of an air conditioning system. It has become common' practice with summer air conditioning units for homes,"oflice buildings, and the like to locate an air-cooled compressorcondenser assembly remotely from the evaporator, the most convenient place usually being outdoors in a suitable weatherproof cabinet. There are many advantages in locating the compressor-condenser assemblies outdoors such -as the elimination of noise in the air-conditioned room and a saving of space inside the building.

While the foregoing advantages are obvious, such arrangements present certain operational problems. With a compressor-condenser assembly in an outdoor location, the condensing rate or capacity of thecondenser is dependent upon the temperature of the outdoor air being forcedby the blower over the condenser. The operating 3,073,132 Patented Jan. 15, 1963 ICC pressure on both the high pressure and low pressure side; of the refrigeration system is also dependent upon the.-

outside ambient air temperature. Thus, when the outside. ambient Atemperature is low, the condensing rate is high resulting in both the high and low operating pressures being lowered. If the outside ambient temperature is low.-

' enough, the suction pressure on the low pressure side of.

Refrigeration Institute, using the design conditions estab,I

the system can drop to -a value where the temperature .of the evaporating coil is loW enough to cause ice to form on the coil surfaces.

To prevent icing of the evaporator coils, the American lished throughout industry, has set 65 F. as a minimum ambient temperature for operating air-cooled air condi. tioni'ng' condensers. If the ambient temperature drops below this figure, an electrical control opens the circuit tot the compressor to shut off the air conditioning system.

While the foregoing arrangement prevents ice from forming on the evaporator coils, it has certain inherent disadvantages.- For example, if the ambient temperaturel for the compressor-condenser assembly hovers at the point of cut-olf, there will be a continual` or and on cycling- ""1- heat removal.

element.

' wherein the outdoor coil serves as'thetevaporator;

avoids evaporator coil icing.

The problem of evaporator 'coil icing; however, does not only exist where the air conditioning system is used for'refrigeration or cooling (i.e., Where the indoor coil serves as the evaporator) but exists as Well when the system is used as a heat pump to heat the indoorvspace and In such a system, icing of the evaporator coil lis likely due totheadditional cooling'- effect on the evaporator coil provided by the cold ambient air, which, conceivably,- could drop'to zero or sub-zero temperatures under severe winter conditions.-

It is` accordingly a primary object of this invention to provide a novel air conditioning system which aiords irnproved" humidity and ventilation regulation land which I lOther objects of this invention are to provide a novel air conditioning system: 1

l) Eiiective for heat pump operation in which eachof the heat-exchange coils serves alternativelyand oppositely as a condenser and an evaporator and in which means are provided toA eliminate icing on the surfaces of each coil during its service as an evaporator;

(2)v Effective for heat pump operation in which each of the heat-exchange coils serves alternatively and oppositely as a condenser and an evaporator and in which separate air flow control units are provided to eliminate icing on the surfaces of each coilduring its service as an evaporator, one of the units additionally being -operative-to pro vide improved humidity and ventilation control;

I(3) Including an air cooled condenser-compressor assembly having an automatic ambient temperature cut-olf, and including novel means to permit the setting of the cut-off temperature at a point much lower than is specified for conventional air cooled compressor and condenser assemblies;

(4) Having novel means for modulating the capacity of an air cooled condenser in accordance with the ambient temperature in which it is operating, the capacity being reduced in proportionV to the drop in temperature below a predetermined point;

(5) Including an improved air cooled compressor and condenser assembly wherein the volume of cooling air moved over the compressor and condenser is decreased at a predetermined drop in ambient temperature by an air ow controlling Vdamper which is positioned by a spiral'bimetalspring responsive to changes in tempera-l ture (6,) Wherein manually operable control means isV provided for eliminating icing on Vthe surfaces of the outdoor coilof said system when said coil is functioning as an evaporator, said means being additionally operative to provide improved humidity and ventilation regulation when said outdoor coil is functioning as a condenser and said system is used to cool or refrigerate.

Another primary object of this invention is to provide simple means to compensate for performance variations caused by variations in duct arrangements and to effectively regulate humidity in operation.

.Still other objects of this invention are to provide humidity and ventilation control means for use in air conditioning systems;

1 (l) Which are reliable and inexpensive; (2) Which are simple in construction and which may be readily and easily operated by users of the system',

V(3) Which have relatively few moving parts and which are provided with a vernier control for line adjustment;

(4) Which include a movable vane or restrictor element positioned in the throat of a centrifugal blower and which are adapted to restrict the flow of air through said throat and to lower the volume per unit time of the air passing through the throat; and

, (5j) Which adjust the ambient humidity by varying the volume per unit time of air passing over the cooling coils of an air cooling system, without varying the power input to the system. 'I'hese and other objectsof the invention will become more fully apparent from the following description and appended claims taken in connection withV the accompanying drawings, showing a preferred structure and embodiment, in which:

FIGURE 1 is a front elevational view of a portion of the indoor assembly incorporating a novel control means of the instant invention;

FIGURE-,v2 is a partly sectioned side view, taken along line 2--2 of- FIG. 1; i

`FIGURE 3 is an enlarged view of a component of K the assembly of FIG. 1 of the instant invention;

kcomponent of the adjustment mechanism;

FIGURE 6 is a View in end elevation of the component shown in FIG. 5;

FIGURE 'l is a detail view of the control knob and dial which form a part of the novel control means of the instant invention;

' lFIGURE 8. is a side elevationpartly broken awayv to show the position of the indoor blower assembly;

FIGUREv 9- is anend elevation partlybroken awayto show. the position of the heat-exchange' coils relative to the indoor blower assembly;

FIGURE 10,v is aside elevation ofv the compressor and outdoor heat-exchange coil assemblyI of this invention with portions; of the side of the housing therefor removed for clarity;

FIGURE ll is an end elevation of the compressor and heat-exchange coil assembly.v taken along the line 1;1 -`11 of FIGURE 10;

' FIGURE 12 is a schematic diagram of the entire system of `the instant invention as arranged for heatelevation of alternative constructions'of the control ele- Y meststof the indoor blower assembly. y

The system in which the novel control means of the instant invention is used is shown schematically in FIG- URE 12. Outdoor heat-exchange coil 90, indoor heatexchange coil 11, compressor 94 and expansion valve 96 are associated with one another as clearly Shown, with valves 100, 102, 104, ,166, 108, 110, 112 and 114 interposed in the system to convert it from refrigeration to heat pump operation, as will more fully be described hereinafter.

'lhe indoor portion of the instant air conditioning system is shown generally in FIGURES 8 and 9. Heatexchange coil 11 is positioned adjacent circular openings 28 in the side walls of blower 2t), whose outlet or neck 318 communicates either directly with a space to be cooled or with ducts (not shown) leading tosuch space. A control cable or Bowden wire assembly 6.6 is operatively connected to an air flow control member 44 (details of this karrangement will be hereinafter described) at one end and to a control assembly designated generally at 13 `at the other. As best seen in FIG- URE 9, a control knob 82 and suitably calibrated dial 83 provide means to manually adjust the essential operating mechanism which provides the novel control of the instant invention.

As is shown more specifically inIFIGURES 1 and 2, the indoor portion of the novel air condition-ing system here involved comprises a centrifugal impeller or blower, designated generally at 20. Blower 20 comprises end walls 22 and 24 and a peripheral wall 26. End walls 22 nd 24 are provided with relatively large circular openings 28 about which the walls are gradually curved inwardly and it is through these openings that air is drawn when the squirrel cage rotor 30 of the blower is rotated. The design and constructionv of the rotor follows standard practice. A shaft 32 on which the rotor, is fixedly. mounted is journalled in bearings 34 which are supported centrally of the openings 28 by spiders 36 attached to each end wall of the blower casing. One end of shaft 32 is suitably connected to a fractional horsepower electric motor for rotating rotor 30'. v

While the vertical dimension of the neck 38 of the blower casing exceeds the diameter of the rotor 30 and isy more than half the height of the casing, its effective cross-sectional area is reduced by a cut-olf 40, which is suitably attached at the junction 42 of the neck 38 and theperipheral wall 26.

Pivotally supported between end walls 22 and v24 and in an area generally designated as the throat. 43 of the blower, is a restricting damper 44. The throat 43 of the blower is the general region of the blower located between the upper edge 46 of the cut-olf 40 and the portion of the peripheral wall 26 of the blower casing approximately opposite said edge, said regiony extending slightly inwardly of a vertical plane passing through the cut-olf 40. Damper 44 is positioned in the portion of throat 43 adjacent peripheral wall 26 of the blower casing where, due to the centrifugal action of rotor 30, the volume of impelled air is greatest.

The lspecific distance which lseparates damper 44 and peripheral wall 26 of the blower casing may be varied within reasonable limits, depending upon the capacity and type of blower used. So long as the damper 44 is positioned generally in the above described portion of the blower casing, however, the surface area of the damper may be considerably less than that of conventional damper-type elements. The damper functions to reduce Y the volume of air per unit time delivered by the blower.

Specific details of construction of damper 44 may be found in Reissue Patent24,42l issued January 28, 1958, to M. W. Patrick, especially in column 4, lines 48-67. As described therein and in other portions of said patent, damper A44 is so designed as to voffer practically no obstruction vtothe ow of air when Ait is in non-restricting position.

Damper 44 Visz-secured to, aushaft 48 which is parallel vventional mechanical pencils.

with the axis of rotor 30 and which is journalled in bearings 50, preferably of a rubber composition especially suited to such purposes and mounted in openings in end walls 22 and 24. Due to the fact that the forces exerted on the portions of damper 44 which are closest to rotor are greater than those exerted against the furthest portions, the damper should preferably be mounted on shaft 48 with its trailing edge substantially further from the shaft than its leading edge. This off-setting will tend to balance these forces and to relieve the stress on the damper.

Fixedly secured to one end of shaft 48 is an arm 52 (see especially FIGURES 3 and 4), which is at approximately 120 to the forward portion 54 of damper 44. Accordingly, when damper 44 is in.its fully operative position, arm 52 will extend downwardly toward rotor 30 in a substantially vertical line and the outer end of damper 44 will project slightly beyond a rubber cushion 56. When in a fully non-restricted position, with damper 44 in a substantially horizontal position, arm 52 is at approximately 30 to the vertical. Stop element 58 is provided in end Iwall 22, immediately beneath the horizontal plane passing axially through shaft 48, to restrict maximum pivotal movement of damper 44 to the horizontal position.

At the lower end of arm 52 is an internally threaded member 60 which passes through an opening 'at the end of said arm and is rigidly xed thereto by brazing or the like. Flange 62, secured t o the end of threaded member 60,` serves to provide added support to maintain rnember 60 rigidly in relation to arm 52. Running ltransversely through internally threadedmember 60 is a centrally threaded bore 64. Wire 80 of a conventional Bowden wire assembly 66 passes through said centrally threaded bore 64 and is secured rigidly therein by means 'of screw 68 vin internally threaded member 60. The Bowden wire assembly 66 is securedat an intermediate point along its length by means of bracket 70k which is secured to the end wall 24 of blower assembly 20. Bowlden wire assembly 66 extends over the peripheral wall 26 of the blower assembly into a housing 72 (see FIGURES 5 and 6), which is secured by' means of nut 74 to front panel 76 of the outer casing of the air cooling assembly.

Control knob 82 is non-rotatably mounted on support shaft 78 and is provided with a suitable indicator mark 79 which, in conjunction with the calibrations 81 on fixed dial 83 (see FIGURE 9) which surrounds said knob,

Housing 72 is a Vconventional assembly designed to i translate rotary motion into longitudinal movement, and

is similar inmany respects to the feed mechanism of con- It comprises generally a sleeve xedly' mounted around shaft '78 and within housing 72, said sleeve l(not shown) having a helical slot there- 'in through which a projection xed normally on wire S0 of Bowden wire assembly 66 projects. The projection on wire 80 also extends through' a longitudinal slot formed in a sleeve of smaller outer diameter than said first mentioned sleeve which is concentric therewith and is rigidly 4fixed against movement with respect to said housing 72 and through which said wire 80 passes. Accordingly, when rotary movement is imparted to shaft 78, thus rotating the outer, helically slotted sleeve, the projection on wire 80 extending through said helical slot will be moved longitudinally forward or rearward, depending upon the direction of rotation of said sleeve. The inner sleeve containing the longitudinal slot prevents rotation of Iwire 80. When wire 80 is moved longitudinally away from front panel 76, in a direction toward said blower assembly 20, the lower end of arm 52 will be moved clockwise as viewed in FIGURE 2. Inasmuch as damper 44 is iixedlyassociated with arm 52, it also will be rotated in a clockwise direction and will, accordingly, restrict the effective throat outlet area 43 of said blower assembly 20. When shaft 78 is so rotated that wire 80 is forced longitudinally toward front panel 76 and away from said blower assembly 20, the lower end of arm 52 will be pulled counterclockwise, thus causing damper 54 to pivot towards its fully inoperative position (i.e., towards stop element 58).

The outdoor portion of the instant air conditioning system is shown in FIGURES 10 and 11. A compressorheat-exchange coil assembly indicated generally at 116 comprises a compressor unit 94, heat-exchange coil 90, and a blower 118 mounted in an elongated housing 120 of rectangular cross-section and having an air inlet opening 122 and an air outlet opening 124 at opposite end s thereof. Blower 118 which is belt driven by a motor 126 is ofY a conventional centrifugal type having a snail shell casing 128 which merges into an air exhaust throat 130 directed toward air outlet opening 124. Mounted in the throat 130 adjacent the top thereof is an air ilow restricting damper 132 shown in closed position in full line and in open position in dotted lines. The damper is mounted on a shaft 134 extending through the side wall of throat 130 to dispose its leading edge 136 closer to the pivot axis than its trailing edge 138 to stabilize the damper (as in the indoor assembly described hereinbefore). 'In general, the details of design and construction of damper 132 are the same as those of damper 44 in the indoor yas4- sembly.

A spiral bimetal spring 140 has its inner end rigidly connected to damper shaft 134 and its outer end adjustably connected to the horizontal wall of a bracket 142 mounted on an outer side of throat 130; Adjustment o f the position of the outer end of spring 140 relative to bracket 142 to vary the tension of the spring is accomplished by a bolt 144, slidable in a slot (not shown) through bracket 142, the bolt 144 clamping the outer en'd of the spring to the bracket at a desired point.

As aforestated, the indoor and outdoor assemblies will be operatively connected in use as shown schematicallyl in FIGURE 12. The reverse-cycle, heat pump operation of the system is as'follows: when the system is used to cool or to refrigerate (i.e., with indoor heat-exchangev coil 11 serving as the evaporator and outdoor coil 90 functioning as the condenser), valves 100, 102, 104 and 106 will be closed and valves 108, 110, 112 and 1114 will be opened; when the system functions to heat (i.e.,`wit'h the indoor coil 11 serving as the condenser and the outdoor coil 90 as the evaporator), valves 100, 102, 104 and 106 will be opened and valves 108, 110, 112 and 114 will be closed. The direction of refrigerant fluid flow, as indicated by arrows in FIGURE 12, will always be fromthe evaporator -to the compressor to the condenser .to the expansion valve to the evaporator.

The Cooling Cycle When the system functions to cool or to refrigerate, several aspects of the instant invention come into play, the first of which relates to the icing of the surfaces `of the indoor evaporator coil due to a drop in ambient (outdoor) temperature below a certain point; Bimetal spring 140 in the outdoor assembly 116 is so adjusted that for temperatures above a certain point, for example 65 F., damper 132 rests in a horizontal position (shown in dotted lines) against a suitable stop 146 whereby the maximum volume of air is drawn through housing 120. 4Should the ambient temperature fall below the point where conventional compressor-condenser units are automatically stopped, birnetal spring 140 will bias the trailing edge 138 of damper 132 toward the top of throat 130 thus reduclng the amount of cooling air being drawn overconvdenser 90.

The Acondensing rate Yor capacity of condenser 90'is thus reducedv proportionately to the decrease in volumeof air drawn through the housing 120. l This reduction in the rate of refrigerant condensation'maintains the low pressure-'on'vthe low side of the refrigeration system at a point above that which yis likely to produce yicing on the evaporater coilV `-11 (in the indoor assembly). Thus, through this invention it is possible to set a much lower cut-olf temperaturethan 65 F. for a condenser-compressor assembly to eliminate the objectionable on and olf cyclingthat koccurs at presently specified cut-off temperatures.

Another aspect of theinvention which comes into play during the cooling cycle'relates to himidity'control and is -primarily concerned with the indoor assembly of the instantair-conditioning system. e Relative humidity Vis a direct function of temperature. The lower the temperature of the air, the less is its capacity to'retain Water vapor. Accordingly, dehumidiiicationof theair passing over the'cooling coils of an air conditioner iSd-proportional to the reduction in the air temperature. When air passes over an evaporating unit or other cooling unit vof an air cooling system, the `air is cooled in direct heatexchange relationship With the unit. One of the factors which will determine the degree of cooling which takes place is lthe length of time .during which the air to be cooled is in heateitchange relation with Vthe cooling unit. The longer tlie contact, the greater the degree of 1 `It follows fromthe above that vif the volume per unit time of the air passing over the'cooling unit isdecreased, the degree of coolingof the air and the dehumidification :willl'iucrease correspondingly for each pass over the cooling-unitandivice versa Thus, ywhen vd'amjtier 44 is Vpivoted toward 'its :How-refstricting position (i.e., when control knob 82 is turned xtowards 'number O on dial 83), greater cooling of the airand,correspondingly, greater dehumidiiication results. Therefore, by adjusting damper 44 between its'fully open 'and fully vrestricted positions (i.e., between number O and 51 'nfdial "183),the`r`elative humidity of the air de'- :livered bythe cooling system may be adjusted within a 'fairly `wide E range.

The Heating Cycle When thef's'y's'tem'functionsto heat, still another "feature Yofthe'instantinvention is significant. As heretofore dis- Ccussed,'evaporator coil-icing problems exist not only when 'theiair-1c'onditionirig system isfunctioning to refrigerate o r @cool butals'o wlie`n-^lit is yonlieat kplump operation and .the outdoor coil iserves 'as the evaporator.k The combination v"fot" cool. air flowing'over coil11l which now functions as "the condenserfand `cold air limpinging on coil 90 which 'now functions 'asthe evaporator may v`cause ice to form'on tli'esurfaceslofgthe latter coil.,V t. t I e A e "Icing Honcoil-90 may :be prevented or reducedv by restricting the position of damper 44 in the indoor assembly by means of the Bowden wire assembly described above and thus reducing the amount of evaporation which will talte place in outdoor evaporator coil `90 as described here- Vtofore in'conn'ection with thesystems operation when on "cooling cycle. ,"In this manner the temperature at which the outdoor evaporator coil'90 will freeze may be reduced by'5jor6 Topermit the `operator of the instant'system to adjust damper`44`to theproper restricted position to avoid'icing on coil 90,'as'uitably calibrated dial (not shown)`rnay be fmounted adjacentxed'dial 8.3 (see FIGURE 9), which dial wouldY indicate the damper position corresponding to Akpredetermined ranges of temperature conditions, By

'checking the. temperature at anygiven time ,the voperator -may'e'asilyadjust the position of damper 44 by'rotating i. control'knob sz.

IAgain, there 'twill be an interplay betweenthe heating and ice-prevention functions of the indoor assembly: as

amis-2 damper 4`4 is restricted, air ow a'cro'ss condenser 11 is re'- ducedl and less total heat is extracted for se in heating. Such restriction, however, serves to decrease the freezing temperature of outdoor coil 90. t These conicti'ng in; terests will, of necessity, have to be balanced onthe basis of prevailing service conditions and heating and icelpre vention demands. l y ,t

It is a well known fact, however, that air flow require ments for eicient heating are much less than those for efficient cooling. For this reason, damper 44 Will be in a partially restricted position duringnormal heating operai tion and thus at least some beneficial effects relative to ice-prevention will be obtained even when heating demands arevgreatest.

As heretofore discussed, birnetal spring 140 is so adjusted that for temperatures above a certain point, damper 132 rests in a horizontal, non-restricting position. Below that point, however, the bimetal spring will bi damper 132 vtowards its fully restricted position. Since ambient outdoor temperatures under heating conditions will usually be below this predetermined point, damper 132 will be in its iiow restricting position substantially throughout the heating cycle. Since there may be times during the heating cycle when it would be more d;sirable to have greater air flow across coll than is obtainable vunder restricted iiow conditions, means (notshown) may be provided to maintain damper 132 in its non-restricted position throughout the heating cycle. Such means may include a vsource of heat (i, e., resistance heater 'element) operative automatically 'or manually when the heating cycle begins to heat birnetal spring to a ternperature greater than that atv/hielt restriction begins. The heat source is rendered inoperative upon `the commencement of the cooling cycle and will accordingly eliminate an otherwise vuncontrolled intiuence on the functioning'of the air conditioning system.

In addition to the inventive aspects discussed above, there are other significant features of the instant invention. YWhen an air conditioning system containing the vnovel ,control means of the instant invention is installed, an initial calibration must be made to 4compensate for variants in air delivery capacity resulting from the varying characteristics of each of the delivery ducts connecting the system to the rooms or other 'spaces to be 4cooled. As heretofore indicated, the volume of cooling air per unit time discharged through the throat of the blower assembly will vary considerably depending upon 4the position of the indoor damper 44. To compensate for the varying duct delivery capacities and static pressure variations, therefore, the position of damper 44 may 4be adjusted to permit the discharge through the throat of the blower assembly of the volume of air per unit `timerequired for optimum operation under normal conditions. This adjustment may be made, of course, by merely rotatingthe control knob -82 until indicator mark 79 thereon is adjacent the pLoper calibration Aon dial 83 on the front panel of the air conditioning unit.

Thus, if the quantity of air per unit time delivered is too great, the control knob should be rotated to move damper 44 toward its-ow-'restricting position, or towards lnumber 0. By so reducing the delivery capacity `of a given duct, however, the respective delivery capacities of other ducts in the system' will be correspondingly re duced. A mean position of the damper between numbers 0 and 5, is selected to strike a balance between the delivery kcapacities ofthe respective ducts in the system and the corresponding cooling'demands ofthe rooms or other spaces to be cooled with which they communicate. The diallsettin'g as obtained lby the 'foregoing procedure will be lsuitable for Vaverage ventilation'and humidity conditions.

Though the foregoing adescription represents the prevferred embodiment ofthe instant novel airconditioning system, various modificationsofthe'system may be vmade without departing from the spririt or essential characteristics thereof. For example, instead of employing a damper such as restricting damper 44 in the indoor portion of the instant novel air conditioning system, the arrangement shown in FIGURE may be used. In this embodiment, a damper 190 is pivotally supported between the end walls of the blower with its axis of rotation passing through the edge 192 of the damper and being parallel to the aXis of rotation of the rotor 193. This damper is located in approximately the same position in the throat 195 of the blower casing as damper 44, in the embodiment heretofore described. Secured to the lower edge of damper 190, at one end thereof, is the end of wire 194 of Bowden wire assembly 196. The other end of the bodwen wire assembly (not shown) is associated with a housing for translating rotational into longitudinal movement and a control assembly identical to that heretofore described inl connection with the indoor assembly (see FIGURES 2 and 5-9). Damper 190 is adapted to be pivoted between a first fully restricted position (shown in dotted lines) and a second, non-restricted position (shown in solid lines) which allows tain the blower in its on position by maintaining the thermostat at a temperature above said lower limit.

unobstructed flow of air through the exhaust throat of the blower. Also, though the system has been set forth as including an indoor manual damper control and an outdoor automatic, bimetal spring contro1,'additional or substitute controls may be added to the system for more effective and selective operation.

l One such control (not shown) usably when outdoor coil 90 is functioning as a condenser (i.e., during cooling cycle) involves the substitution of a conventional thermostat for bimetal spiral spring 140 and its accompanying assessories (i.e., bracket 142 and bolt 144), said thermostat performing a function substantially identical to that of bimetal spiral spring 140 (i.e., the prevention of freezing of indoor coil 11). The thermostat is positioned so that it is responsive to the temperature of the ambient outdoor air. When the temperature falls below a predetermined point (i.e., 65 F.), the thermostat operates a solenoid which will move damper 132 to its restricted position. In so doing, the solenoid will overcome the opposing force of a spring which normally biases the damper toward its non-restricted position. When the ambient temperature rises above 65 F., the thermostatsolenoid circuit will be broken and the spring bias will force damper 132 back to its non-restricted position.

To overcome the tendency of the thermostat-solenoid circuit to urge damper 132 toward its restricted position during the heating cycle (the ambient temperature in such case would normally be below 65 F the circuit may be disconnected during said heating cycle.

A conventional thermostatic structure as above described (or an outdoor bimetal spiral spring structure, as the case may be) may be effectively utilized to prevent freezing of the indoor evaporator coil 11 during cooling cycle when the outdoor ambient temperature drops below 65 F. There is an outdoor ambient temperature lower limit, however, below which the indoor evaporator coil 11 will freeze even when damper 132 is in its fully restricted position.

To avoid freezing of the indoor coil 11 at this lower temperature limit, a conventional thermostat, responsive to outdoor ambient temperature, is operatively connected to a relay circuit which is designed to shut off power to the blower 118 when closed by means of the thermostat. When the ambient temperature reaches said lower limit, the relay circuit will be closed and the outdoor blower 118 will be shut olf. lFreezing of the indoor evaporator coil 11 will accordingly be avoided.

To prevent the thermostat-relay circuit from keeping 4the blower in its off position during the heating cycle, the thermostat-relay circuit must either be disconnected or, as heretofore discussed in connection with bimetal spring 140, heating means may be provided -to main- Another such control (not shown) usable when outdoor coil is functioning as an evaporator utilizes an additional Bowden wire assembly equivalent to that described in connection with the control of indoor damper 44. One end of the Bowden wire is operatively connected to damper 132 through elements such as shaft 48, arm 52 and internally -threaded member 60 (see FGURES 3 and 4), the other end being connected to a suitable housing for translating rotary into longitudinal movement which may be controlled by a suitable control knob 1ocated in the proximity of control knob 82. A dial calibrated to indicate the position of damper 132 corresponding to predetermined ranges of outdoor ambient temperature may be provided adjacent the control knob. By checking the outdoor ambient temperature at any given time, the operator may easily adjust the position of damper 132 to modulate the air flow over heat-exchange coil 90 when it is functioning as an evaporator. This will provide effective ice-prevention control to supplement that afforded by restriction of indoor damper 44.

This additional manual control may be used in lieu of and will thus eliminate the necessity for heating means to maintain damper 132 in its non-restricted position throughout the heating cycle, as heretofore described.

lf desired, the Bowden Wire need not be physically connected to damper 132 as described above but may be physically connected to an adjustable stop as shown in FIGURE 13. Wire 160 of a Bowden wire assembly 162 is secured at one end by means of a screw 163. to internallyv threaded angle element 164 which ispivoted for rotative movement about a pivot 1.66. The other end of wire 160 (not shown) is connected to a housing for translating rotary into longitudinal movement which may be controlled by a control knob located near control knob 82, as has been more fully described above. Since no heating means to maintain damper 132 in its non-restricted position during the heating cycle is present, bimetal spring will bias damper 132 toward its fully restricted position (shown in dotted lines) under normal ambient outdoor heating cycle conditions (as heretofore discussed). When it is desired to maintain damper 132 in its non-restricted position, therefore, the control knob should be rotated so that wire is moved to the right (as shown in FIGURE 13). Angle element 164 will be pivoted about pivot 166 in a clockwise'direction and the end 168 of angle element 164 urging against damper 132 will overcome the biasof bimetal spring 140 and force damper 132 toward its non-restricting position.

When it is desired to restrict damper 132, the control knob should be rotated so that angle element 164 is pushed counterclockwise, allowing the normal bias of bimetal spring 140 to urge damper 132 toward its flowrestricting position.

ln addition to the above modification (or independently thereof, if desired), a bimetal spiral springl (see FIG- URE 14)v set to function during the heating cycle in the manner described in Patrick Reissue patent 24,421, mentioned above, may be added to supplement the heat-controlling function of the indoor manually operable control during heating cycle. As described in said reissue patent, a bimetal spring element used in the manner therein disclosed, avoids the discomfort attending the operation of conventional air conditioning systems upon the starting and stopping thereof.

Where such a bimetal spring is used as taught in Patrick reissue patent, howevena modification of the basic indoor manual control for damper 44 must be made for operation during the heating cycle. Such a modication is shown in FIGURE 14. A bimetal spring assembly ,indicated generally at 170 is identical to that described above for use in connection with the outdoorblower asapr-susa sembly. vWire' tlgofBowd'en wire assembly 66 is secured in an internally threaded connecting link 172 by means of screw 174. The other end of connecting link 172 is pivotally connected to one end of a crank arm 176` which is rigidly secured at its other end to a sleeve 17S which is rotatable about an end portion of damper-supporting shaft 48. A stop pin 18o projects out from shaft 48 through a slot 18.1 in sleeve 178. The other end of wire 80 is secured to knob 82 through housing 72 as has been heretofore described.

Whenrthe system is used during the heating cycle, the damper 44 will assume the full open position as shown in FIG. 14; If it is desired to restrict the air flow to protect the outside evaporator coil or for other reasons, knob 82 is turned suciently to move wire 8i) to the right (see FIGURE 14) which, in turn, will rotate sleeve 178 clockwise carrying stop pin 180 and damper 44 with it; This construction permits thel bimetal springV to move'freely toY urge damper 44 toward its restricted pos'jition during. the initial surge of cold air at the beginning of the heating operation.

During summer operation, the bimetal spring will normally function to maintain the damper in a restricted position. This action may be prevented by setting control knob 82 atl the desiredy position. For example, if the wire 80 is-moved to the left the sleeve 17S will be ro- Vtated in a counterclockwise direction carrying pin 180` with it tomove damper 44 away from its restricted position; any desired amount.-

In this manner,1the advantages of the Patrick structure and operationimay be obtained wtihout undue interference with `the beneficial functions described hereinbefore.

In lieu of the bimetal spiral spring structure, an alternative structure employing a conventional thermostat may'be utilized to avoid the discomfort attending the starting and stopping of the blower during heating cycle operation. In such an embodiment a conventional thermostat (not shown) is positioned in the indoor blower casing in such a manner that it will s ense any change in the temperature of the air delivered by the blower. A't a predetermined temperature, i.e., 110 F., the thermostat operates aI solenoid v(not shown) which will move the damper to non-restricted position. In so doing, the

solenoid will overcome the opposing force of a springV (not shown) which normallytbiases the damper toward its vrestricted position. When the temperature of the air passing Vover the thermostat falls below the predetermined temperature, the thermostat-solenoid circuit will be broken and'the spring bias will force the damper back to its re- Stricted f positiont This embodiment functions, in principle, substantially the same as the bimetal spring structure described above. Where the'fth'ermostat is employed, however, only two position operation is obtainable, as contrasted withl the wide-range control provided bythe bimetal spring structure.

Though the-spring biaswould maintain ythe damper in a restricted position when the system is operating on cooling cycle, this-force may be overcome by the mankual adjustment offcontrol `knob 82.

To supplement the bimetalA spiral spring or the alternative thermostatstructure above discussed, an additional thermostat (not shown) may be placed in direct heat exchange contact with the indoor heat-exchange coil to control a Vconventional relay circuit (not shown) which, in turn, will shut off the blower whenever the temperature of the indoor coils falls below aY certain temperature, i.e., 100 F;

The use ofV sucha thermostat eliminates the problem 12 ducts) would be exhaustedbythe blower until such time as the coil temperature increased sufficiently; In view of the fact that the indoorheat-exchange coil functions also as anevaporator duringpthe'coolingcycles, it is necessary of course to` disconnect the thermostat-relay circuitv to permit blower operation during normal cooling periods;

If'desired the air c-onditioningsystem embodying novel control means as described herein may also be used solely to Ventilate, by operating indoor blower 2.0 without turning on the refrigerant unit. By adjusting the position of damper 44', more .or less air` may beinjected into the space to be ventilated. Also', while this invention is particularly suited'for use in cases wherein one of the heat-exchange units is located outdoors remotely from the other heatexchange unit, it is also useful as a modulating control in a self-contained'unit, wherein all of the units` are lo-A cated indoors. A

The invention may beembodied in still other specific forms without departing from the spirit orl essential .characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the yappended claims rather than by the foregoing description, andall changes which comeA within the meaning and range of equivalency ofthe claims are therefore intended to be embraced therein'. l

What is claimed'and desired to-be'secured by United States Letters Patent is: p

li An air conditioning'system comprising: first 'and second heat-exchange units; a" closed 'conduit system connecting said units; a compressor and expansion valve means in said lconduit system; valve means in said conduit system to permit selective alternate operation of saidiirst and second units as acondenser and as an evaporator; a first blower adapted'to blow air over saidtrst unit; a second blower adapted to blow air over said secondunit; each of said'blowers havingran air exhaust throat; an air damper plate pivotally mounted in the throat of each blower for controlling the Volumeof air passingtherethrough'; and a temperature responsive control device to urge said damper plate in `said first blower in adirection to decrease the volume of air' passing through the throat of 'said blower upon a drop in temperature whereby the volume of air passing over said tirst'unit is decreased proportionately,

2. The air conditioning system of claim l wherein the air damper plate in said iirst 'blower is pivotally mounted on. a shaft in the throat of said blower and wherein said temperature-responsive means comprises a spiral bimetal spring having its inner end connected tosaid damper plate shaft, a bracket fixedly positioningrthe outer end of'said spring.

3.`Th`e air conditioning system of'claim ladditionally comprising meansv to selectively maintain the air damper plate in said 'first blower in its fully openposition.

4." The ai conditioning system of claim l additionally comprisingadjustable stop means effective selectively to overcome the tendency of'said damper plate in said vfirst blower to pivot to.a position, todecrease the volume of air passing through the throat of saidkr blower upon .a drop in. temperature.

5. An air conditioning system comprising an elongated housingk having a pair of air openings therein; a compressor and-a first heat-exchangecoil mounted in said housing betweeny said openings; va first blower mounted in said housing adapted to blow air into one of said openings and over said compressor and rst heat exchange coil and out the other opening; a second heat exchangek coil; a secondzbloweradapted Vto blow air over said second coil and ultimately into, a space to beair conditioned; a closed conduit systern connectingsaid coils'and saidcompressor; an expansion valvemeansin said conduit system; valve means insaid conduit system to permit selective alternate operation oflsaidfiirst and second coils as a condenser and as an evaporatorreach of said first and second blowers 13 having an air exhaust throat, an air damper plate pivotally mounted in the throat of each of said blowers for controlling the volume of air passing therethrough; manual means operative to pivot one of said air damper plates, and temperature responsive means operative to pivot the other air damper plate in a direction to decrease the volume of air passing through the throat of its associated blower upon a drop in ambient temperature when its associated heat exchange coil is operating as a condenser.

6. A compressor-condenser assembly for an air conditioner comprising an elongated housing having an air inlet opening and an air outlet opening therein, a compressor and a condenser mounted in said housing between said inlet and outlet openings, a, blower mounted in said housing having an air exhaust throat mounted in said air outlet opening, said blower being operative to draw air through said inlet opening and over said compressor and condenser before entering said throat, an air damper plate pivotally mounted on a shaft in said throat, the distance between the shaft axis and the trailing edge of the plate being sufcient for the trailing edge of the plate to engage a wall of the throat when the plate is pivoted in one direction, `a spiral bimetal spring having its inner end connected to said damper plate shaft, a bracket fxedly positioning the outer end of said spring, said bimetal spring being operative to pivot said damper plate in said one direction to a position to decrease the volume of air passing through said throat in response to a drop in the ambient air temperature whereby the volume of air passing over said compressor and condenser is decreased proportionately.

7. The assembly of claim 6 in which said compressor is mounted adjacent said air inlet opening.

8. The assembly of claim 6 in which said air inlet and outlet openings are at opposite ends of said housing, said compressor being mounted adjacent said air inlet opening.

9. The assembly of claim 6 in which said blower is a centrifugal blower having a snail shell casing merging with said discharge throat.

10. A compressor-condenser assembly for an air conditioner comprising an elongated housing having an air inlet opening and an air outlet opening at opposite ends thereof, a compressor and a condenser being mounted in said housing between said inlet and outlet openings with the compressor being mounted adjacent the inlet opening, a centrifugal blower mounted in said housing, said blower having a snail shell casing merging into an air exhaust throat disposed in said outlet opening, said blower being operative to draw air through said inlet opening and over said compressor and condenser before entering said throat, an air damper plate pivotally mounted on a shaft in said throat for decreasing the volume of air passing therethrough, said damper plate having a leading edge and a trailing edge disposed transversely of the-air stream in said throat, the shaft axis being nearer the leading edge of the plate than the trailing edge thereof, the distance between the shaft axis and the trailing edge of the plate being suficient for the trailing edge of the plate to engage a wall of the throat when the plate is pivoted in one direction, a spiral bimetal spring having its inner end connected to said damper plate shaft, a bracket xedly positioning the outer end of said spring, said bimetal being operative to pivot said damper plate in said one direction to a position to decrease the volume of air passing through said throat in response to a predetermined drop in ambient air temperature whereby the volume ofv air passing over said compressor and condenser is decreased proportionately.

References Cited in the file of this patent UNITED STATES PATENTS 1,752,830 Bliss Apr. 1, 1930 2,317,104 Moore Apr. 20, 1943 2,619,812 Burgess Dec. 2, 1952 2,656,685 Borgerd Oct. 17, 1953 2,711,080 Jewell lune 2l, 1955 2,718,119 Prince Sept. 20, 1955 2,719,666 Hollingsworth Oct. 24, 1955 2,721,704 Patrick Oct. 25, 1955 2,892,324 Quick June 30, 1959 2,958,208 Braden Nov. l, 1960 

1. AN AIR CONDITIONING SYSTEM COMPRISING: FIRST AND SECOND HEAT EXCHANGE UNITS; A CLOSED CONDUIT SYSTEM CONNECTING SAID UNITS; A COMPRESSOR AND EXPANSION VALVE MEANS IN SAID CONDUIT SYSTEM; VALVE MEANS IN SAID CONDUIT SYSTEM TO PERMIT SELECTIVE ALTERNATE OPERATION OF SAID FIRST AND SECOND UNITS AS A CONDENSER AND AS AN EVAPORATOR; A FIRST BLOWER ADAPTED TO BLOW AIR OVER SAID FIRST UNIT; A SECOND BLOWER ADAPTED TO BLOW AIR OVER SAID SECOND UNIT; EACH OF SAID BLOWERS HAVING AN AIR EXHAUST THROAT; AN AIR DAMPER PLATE PIVOTALLY MOUNTED IN THE THROAT OF EACH BLOWER FOR CONTROLLING THE VOLUME OF AIR PASSING THERETHROUGH; AND A TEMPERATURE RESPONSIVE CONTROL DEVICE TO URGE SAID DAMPER PLATE IN SAID FIRST BLOWER IN A DIRECTION TO DECREASE THE VOLUME OF AIR PASSING THROUGH THE THROAT OF SAID BLOWER UPON A DROP IN TEMPERATURE WHEREBY THE VOLUME OF AIR PASSING OVER SAID FIRST UNIT IS DECREASED PROPORTIONATELY. 